9. Microanatomy of the cardiovascular system

Question 1

Properties of cardiac myocytes

Answer 1

single nucleus

Transverse-tubule system

SR less extensive than in skeletal muscle

Mitochondria take up 30-40% of cell volume

Branched cells linked together by intercalated disks

Question 2

Annulus fibrosus cordis

Answer 2

Dense connective tissue

encircles the base of the aorta and pulmonary artery

provides an attachment site for the semilunar valves

Question 3

Elastic arteries

Answer 3

Thick medial layer

high levels of elastin and collagen

Large vessels.

Question 4

Muscular arteries

Answer 4

Large amounts of smooth muscle in the media

thick adventitial layer

Medium-sized vessels.

Question 5

Continuous capillaries

Answer 5

tight junctions join endothelial cells

partially leaky

Question 6

Fenestrated capillaries

Answer 6

gaps through endothelial cells

Question 7

Sinusoid capillaries

Answer 7

large diameter

discontinuous endothelium

free exchange between blood and interstitial fluid

Question 8

The role of calcium ions in contraction of smooth muscle

Answer 8

NO TROPONINS in smooth muscle

cell undergoes AP

calcium ions enter from IF

calcium ions carry some of current for the AP

calcium ions bind to calcium-calmodulin complex

activates MLCK enzyme

MLCK enzyme phosphorylates light chains of myosin allowing them to bind to actin

Question 9

What does the lymphatic system do?

Answer 9

Tissue drainage

Some absorption in the small intestine

Immunity